Stripper for a work roll of a rolling stand

ABSTRACT

The present invention relates to a stripper ( 11 ) for a work roll of a rolling stand, in particular a hot rolling stand, wherein the stripper tip ( 11 ) has a stripper tip ( 5 ) that makes a contact with the work roll ( 1 ), and a first screening element ( 8 ) for screening a rolled material ( 10 ) from cooling water of the rolling stand, wherein there is provided a second screening element ( 6 ) for screening the first screening element ( 8 ) from being thermally loaded by the rolled material ( 10 ).

FIELD OF THE INVENTION

The present invention relates to a stripper for a work roll of a rolling stand in particular a work roll of a hot rolling stand, and an apparatus for cooling a work roll of a rolling stand.

STATE-OF-THE ART

In rolling stands, in particular in hot rolling stands, strippers are used for upper and lower work rolls at an inlet and an outlet of a respective rolling stand. The strippers typically permanently make contact with the work rolls during a rolling operation. The contacts are carried out with a stripper tip that makes contact with a respective work roll. The strippers are formed for screening the surface of the rolled material from the roll cooling water and are in a position to eventually strip the rolled material clinging to the work rolls.

During a rolling process, the work rolls are subjected to high thermal loads. The heat, which is applied to the work rolls, is transferred in the rolling gap primarily by contact of the work rolls with the rolled material, wherein the input heat energy is increased additionally by a rolling heat produced as a result of plastic deformation of the rolled material. Further, friction heat, which is produced by friction between the rolled material and the work roll and in the contact region between the work roll and the usually provided, back-up roll, is also applied to the work rolls.

In order to prevent a premature or excessive wear of the work rolls by thermal loads, the roll cooling is of a paramount importance. In particular, it is attempted, by an appropriate outer cooling of the roll, in particular at the outlet side, to remove the work roll heat, which is applied to the roll outer surface in the rolling gap, efficiently and to a most possible extent, as soon as possible after the rolled material exits from the rolling gap to prevent penetration of the heat into the depth of the roll.

Correspondingly, the cooling water is sprayed on the work roll as soon as possible. The strippers take care that the cooling water, which is sprayed on the work roll from outside, makes no contact with the rolled material and/or reduction of the quality of the rolled material is prevented.

Because the work roll outer cooling takes place as soon as possible after the roll material exits the rolling gap, the strippers are arranged above the rolled material as low as possible and are arranged as close as possible to the roll gap. The strippers forms partially a component of respective inlet and outlet guides and are correspondingly at least rotatably supported or often are even mounted on gimbals. The strippers are pressed against respective work rolls either pneumatically or hydraulically or by a contact with a pressure mass.

Because the stripper typically is arranged very low above the rolled material, it is subjected to a high thermal load on its side adjacent to the rolled material, on one hand. On its side remote from the rolled material, the stripper is impacted by the cooling water which it should prevent from reaching the rolled material. Correspondingly, the prior art strippers are subjected to very high temperatures on one of their sides and to cooling water temperatures on their other sides. Thereby, unavoidably, a different thermal expansion on respective stripper sides takes place which results in wobbling of the stripper and, e.g., no complete sealing can be provided, e.g., in the middle region of the rolled material.

Stripper elements are disclosed, e.g., in DE 2008 019 548 A1 and in EP 0 899 030 A2.

DESCRIPTION OF THE INVENTION

Correspondingly, the object of the invention is to provide a stripper and a device for cooling work rolls of a rolling stand which would insure a better sealing of the cooling water during operation.

This object is achieved with a stripper having features of claim

Advantageous embodiments are set forth in sub-claims.

Correspondingly, the stripper for a work roll of a rolling stand, in particular of a hot rolling stand, has a stripper tip for making contact with the work roll of the rolling stand, and a first screening element for screening a rolled material form cooling water of the rolling stand is provided.

According to the invention, there is provided a second screening element for screening the first screening element from being thermally loaded by the rolled material.

By providing a first screening element for screening the rolled material from the cooling water and a second screening element for screening the first screening element from being thermally loaded by the rolled material, it could be achieved that both screening elements, namely the first screening element and the second screening element can be so adapted to respective prevailing thermal conditions that the stripper tip makes a constant contact with a respective work roll.

The first screening element is advantageously spaced from the second screening element by a distance from 0.5 cm to 5 cm, preferably, by a distance from 1 cm to 4 cm, and even more preferably, by a distance from 2 cm to 3 cm.

In this way, screening of the first screening by the second screening element can be achieved.

In addition, in this way, a parallelogram effect is achieved when the first screening element and the second screening element are subjected to a different temperature expansion due to different temperature action.

According to an advantageous embodiment, and insulation element is provided between the first screening element and the second screening element for thermally insulating both screening elements from each other.

The second screening element that serves for screening the thermal load applied by the rolled material is subjected to noticeably higher temperature than the first screening element that keeps the cooling water away from the rolled material. In this way wobbling of the stripper can be prevented because a noticeable temperature difference of different sides within a single material, which is known in the state-of-the art, is prevented. Thus, the stripper according to the present invention wobbles much less or mostly not at all, so that the screening by the stripper of the strip middle region can be achieved and set in a controlled manner.

According to a particularly advantageous embodiment, at least one third screening element spaced from the first screening element and/or from the second screening element, and/or at least one second insulation element is arranged between the third screening element and the first and/or second screening element.

Thereby, a sandwich structure is provided advantageously for at least two screening elements. This can be achieved with a corresponding multi-part construction of the stripper in form of a sandwich construction, in particular with the inwardly located insulation layer. The insulation layer separates the side with a high thermal load from the side with a low thermal load.

Advantageously, the two screening elements are connected with each other by screw means, preferably with use of spacers.

A particular efficient construction is achieved with at least two screening elements which are spaced from each other and are connected with each other by screw means and/or a spacer.

In a particularly advantageous embodiment the stripper tip is formed as a separate constructional component that can be quickly replaced, using a simple lock. By providing a stripper as a separate component, it is achieved that a defective and/or used stripper tip can be replaced quickly and efficiently, without interrupting the apparatus operation for a noticeably long period of time. On the other hand, the stripper tip can be formed of another material than the first and second screening elements.

Advantageously, the stripper is pivotally supported on the rolling stand as a unit so that a contact of the stripper with the outer surface of the work roll is insured even if the work roll axis moves or is displaced.

In order to achieve an adequate screening, at least one screening element extends, as one piece, over the support length of the work roll.

The object of the invention is also achieved with an apparatus for cooling of work roll of a rolling stand having the features of claim 10.

An apparatus for cooling a work roll in a rolling stand includes a cooling water-spraying apparatus for spraying cooling water onto the work roll, and the above-described stripper, wherein the stripper is arranged between the rolled material and the cooling water-spraying apparatus.

BRIEF DESCRIPTION OF THE DRAWING:

Advantageous further embodiments and features of the present invention will be explained in detail by the following description of the drawing figure. It is shown in:

FIG. 1 an upper outlet stripper according to an exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Below, a preferred embodiment will be described with reference to FIG. 1.

Correspondingly, there is provided a stripper 11 the stripper tip 5 of which makes a contact with a work roll 1 of a not explicitly shown, rolling stand of a hot rolling train. The work roll 1 is supported, in a known manner by a back-up roll 2.

The work roll 1 is cooled in a known manner. In addition to a known inner cooling of the work roll 1, it is also cooled from outside by being sprayed with cooling water.

With the outer cooling, a cooling water apparatus 3 cools the work roll 1 after a rolled material 10 left the rolling gap. The cooling water apparatus 3 applies a large amount of water directly to the work roll 1. The stripper 1 is arranged between the rolled material 10 and the cooling water apparatus 3 in order to prevent contact of the rolled material 10 with the cooling water. Cooling of the rolled material 10 within a respective rolling mill train is undesirable.

It is advantageous when the stripper 11 with the stripper tip 5 is so arranged that the cooling water comes into contact with the work roll 1 as soon as possible after a respective surface element exits the rolling gap. In other words, the stripper tip 5 is advantageous arranged as close as possible to the rolling gap. With this rapid cooling, it is achieved that the heat from the outer surface of the work roll 1 does not penetrate deep into the work roll 1 or that the volume of the work roll does not change and it, correspondingly, cannot be damaged.

The stripper tip 5 extends advantageously over the entire support length of the work roll 1 in order to achieve uniform stripping and uniform cooling of the work roll 1.

The stripper 11 is pivotally supported by a bearing journal 4. A pneumatic cylinder 12, which is arranged at an end of the stripper 11 opposite the stripper tip 5, presses the stripper tip 5 against the work roll 1. The bearing journal 4 is correspondingly arranged between the stripper tip 5 and the pneumatic cylinder 12.

In addition to the stripper tip 5, the stripper includes a screening element 8 for screening the rolled material 10 from the cooling water applied by the cooling water apparatus 3.

There is also provided a second screening element 6 for screening the first screening element 8 from being thermally loaded by the rolled material 10. The second screening element 6 is spaced from the first screening element 8. In other words, there are provided two screening elements 8 and 6 spaced from each other, wherein the first screening element protects the rolled material 10 from a contact with the cooling water from the apparatus 10, and the second screening element 6 protects the first screening element from an excessive heat.

The second screening element 6 is provided on the side of the stripper 11 adjacent to the rolled material 10. Correspondingly, the second screening element 6 screens the large radiation heat of the rolled material 10. In this way, the excessively large temperature gradient in the thickness direction of the screening element 8 is prevented, whereby a disadvantageous heat deformation of the stripper 11 can be avoided.

Even when, in the considered embodiment, heat deformation of the first screening element 8 and/or the second screening element 6 takes place, a parallelogram displacement of both screening elements 8 and 6 relative to each other is produced in a typical manner and which is compensated right away by the stripper 11 being pivoted about the bearing journal 4 by the pneumatic cylinder 12.

The first screening element 8 and the second screening element 6 are connected with each other by a fastening element 9 which is shown schematically. In order to insure spacing between the first screening element 8 and the second screening element 6, advantageously, there is provided a fastening element 9, e.g., a screw element, in combination with spacing elements.

As shown in FIG. 1, there is provided, between first screening element 8 and the second screening element 6, an insulation element 7 that thermally insulates both plate-shaped screening elements 8 and 6 from each other. The spacer in the fastening element 9 also serves for preventing the insulation element 7 from being crushed or destroyed upon connection of the first screening element 8 with the second screening element 6.

By forming a sandwich structure, bulging of the stripper 11 during operation because of different thermal loading of both sides of the stripper 11, is prevented to a most possible extent. Correspondingly, a stable and uniform striping with the stripper tip 5 is insured.

In addition to the structure of the stripper 11 with a first screening element 8 and a second screening element 6 and an insulation element 7 arranged therebetween and which is shown in FIG. 1, a construction of stripper 11 is contemplated, according to the present invention, which has more than two screening elements, e.g., three or four which likewise are separated from each other by an insulation layer and are spaced from each other.

LIST OF REFERENCE NUMERALS

-   1 Work roll -   2 Back-up roll -   3 Cooling water-spraying apparatus -   4 Bearing journal for positioning of the stripper -   5 Stripper tip -   6 Second screening element -   7 Insulation element -   8 First screening element -   9 Fastening element -   10 Rolled material -   11 Stripper -   12 Pneumatic cylinder 

1. A stripper (11) for a work roll of a rolling stand, in particular a hot rolling stand, comprising a stripper tip (5) for making contact with the work roll (1) of the rolling stands, and a first screening element (8) for screening a rolled material (10) from cooling water of the rolling stand, characterized by wherein a second screening element (6) for screening the first screening element (8) from being thermally loaded by the rolled material, and wherein an insulation element (7) is provided between the first screening element (8) and the second screening element (6) for thermally insulating both thermal elements (8, 6) from each other.
 2. A stripper according to claim 1, wherein the first screening element (8) is spaced from the second screening element (6) by a distance from 0.5 cm to 5 cm, preferably, by a distance from 1 cm to 4 cm, and even more preferably, by a distance from 2 cm to 3 cm.
 3. (canceled)
 4. A stripper according to claim 1, wherein there is provided at least one third screening element spaced from the first screening element (8) and/or from the second screening element (6), and/or at least one second insulation element is arranged between the third screening element and the first and/or second screening element.
 5. A stripper according to claim 1, wherein at least two screening elements (6, 8) form a sandwich structure with each other.
 6. A stripper according to claim 1, wherein the at least two screening elements (6, 8) are connected with each other at a distance from each other by screw connection means and/or a spacer.
 7. A stripper according to claim 1, wherein the stripper tip (5) is formed as a separate constructional component and is advantageously connected with the first screening element (8) and/or the second screening element (6).
 8. A stripper according to claim 1, wherein the screening elements (6, 8) are pivotally supported relative to the rolling stand.
 9. A stripper according to claim 1, wherein at least one screening element (6, 8) extends, as one piece, over the support length of the work roll (1).
 10. An apparatus for cooling a work roll (1) of a rolling stand, comprising a cooling water-spraying apparatus (3) for spraying cooling water on the work roll (1); and a stripper (11) arranged between the rolled material (10) and the cooling water-spraying apparatus (3), wherein the stripper has a striper tip (5) for making contact with the work roll (1) of the rolling stands, a first screening element (8) for screening a rolled material (10 from cooling water of the rolling stand, a second screening element (6) for screening the first screening element (8) from being thermally loaded by the rolled material, and an insulation element (7) provided between the first screening element (8) and the second screening element (6) for thermally insulating both thermal elements (8, 6) from each other. 